1. Technical Field
The present invention relates to a photoelectric encoder scale used in a linear encoder, a rotary encoder, or the like, and a manufacturing method of such a scale.
2. Related Art
For example, a photoelectric encoder has a main scale which extends along a measurement axis and an index scale which is disposed so as to be movable relative to the main scale. The photoelectric encoder is configured in such a manner that a light receiver receives, through the index scale, light that is reflected from the main scale after being emitted from a light source and incident on the main scale through the index scale. Each of the main scale and the index scale is formed with a grating (graduations) at a prescribed pitch. Various methods for forming a grating on each of the main scale and the index scale are known (Patent documents 1-8).
However, in these related-art techniques, the manufacturing cost is very high because a film forming apparatus for grating formation requires a vacuum chamber (Patent documents 1, 2, 5, and 6), it is difficult to form a grating with high accuracy (Patent documents 3, 4, 6, and 8), or the detection accuracy is lowered due to reduction of the reflection light quantity (Patent document 7).